基于Sigmoid函数的离轴照明光源全参数解析模型

Parametric analytical model for off-axis illumination sources based on Sigmoid function

本文提出一种全面描述光刻机离轴照明光源物理分布特性的全参数解析模型,该模型采用Sigmoid函数作为构造各种主流离轴光源解析模型的核函数.提出通过加入光源全参数修正项来表征真实光源的各种物理畸变和偏差,全参数修正项可展开为傅里叶级数形式,相应级次的傅里叶系数具有特殊的物理意义,可分别代表偏心、倾斜、椭偏等形式的光源畸变,为光刻分辨率增强技术及其相关领域提供了仿真条件与理论依据,具有重要的应用价值.

This paper proposes a parametric analytical source model for overall representation of the physical distribution property of off-axis illumination sources in lithographic tools.A Sigmoid function is adopted as a kernel function to construct the analytical model for the multiple mainstream off-axis sources.Corrected parametrical terms are subsequently presented for characterization of different physical distortions and deviations of real illumination sources.The corrected parametrical terms can be decomposed into Fourier series which have the special physical meaning of respectively indicating different distortion types including shift of the center,tilt,ellipticity,etc.The proposed analytical model provides both simulation condition and theoretical basis for the resolution enhancement technique and the related research fields,thus has important applications.